+C<sync> synchronizes a file's in-memory state with that on the
+physical medium. C<sync> does not operate at the perlio api level, but
+operates on the file descriptor (similar to sysread, sysseek and
+systell). This means that any data held at the perlio api level will not
+be synchronized. To synchronize data that is buffered at the perlio api
+level you must use the flush method. C<sync> is not implemented on all
+platforms. Returns "0 but true" on success, C<undef> on error, C<undef>
+for an invalid handle. See L<fsync(3c)>.
+
+=item $io->flush
+
+C<flush> causes perl to flush any buffered data at the perlio api level.
+Any unread data in the buffer will be discarded, and any unwritten data
+will be written to the underlying file descriptor. Returns "0 but true"
+on success, C<undef> on error.
+
+=item $io->printflush ( ARGS )
+
+Turns on autoflush, print ARGS and then restores the autoflush status of the
+C<IO::Handle> object. Returns the return value from print.
+
+=item $io->blocking ( [ BOOL ] )
+
+If called with an argument C<blocking> will turn on non-blocking IO if
+C<BOOL> is false, and turn it off if C<BOOL> is true.
+
+C<blocking> will return the value of the previous setting, or the
+current setting if C<BOOL> is not given.
+
+If an error occurs C<blocking> will return undef and C<$!> will be set.